Celeriac Soup With Hazelnut Crumble

There's something about celeriac that catches people off guard—most home cooks walk right past it at the market, intimidated by that knobbly exterior. I discovered its magic on a grey autumn afternoon when a farmer handed me one along with a knowing smile, saying it would transform into something silky and unexpected. One roasted batch later, I was hooked, and this soup became my quiet ritual whenever the weather turns cool and I need something that feels both elegant and deeply comforting.

I made this for my partner on a Sunday when we'd both had overwhelming weeks, and watching their face soften at that first spoonful reminded me why cooking matters so much. The soup seemed to pause time for a moment, and we sat at the kitchen table longer than planned, just talking and eating slowly, the hazelnut topping crunching between bites like punctuation to our conversation.

Ingredients

• Celeriac (about 700 g): This knobby root vegetable is your foundation—roasting it first concentrates its subtle, slightly sweet celery-like flavor and makes the blending remarkably smooth.
• Onion and garlic: These aromatic base notes build the soup's depth; don't skip the step of sautéing them in oil first, as it releases their sweetness.
• Potato (about 150 g): Acts as a natural thickener without needing cream or flour, keeping the soup silky and giving it body.
• Vegetable broth (900 ml): Quality matters here—a good broth with subtle flavor will let the roasted celeriac shine rather than compete.
• Olive oil (2 tbsp): Use one tablespoon for roasting the celeriac to encourage browning, and another for sautéing the aromatics.
• Heavy cream (100 ml, optional): Adds luxury and rounds out the flavors; plant-based cream works beautifully if you prefer dairy-free.
• Sea salt and black pepper: Taste as you go—celeriac's delicate sweetness needs seasoning to truly sing.
• Ground nutmeg (1/4 tsp): A small pinch is crucial; it whispers warmth without announcing itself, tying all the flavors together.
• Hazelnuts (60 g): Raw whole hazelnuts toasted in butter develop a deep, almost chocolatey richness that contrasts beautifully against the soup's smoothness.
• Butter (1 tbsp) or olive oil: Toasting the hazelnuts in fat brings out their inherent nuttiness and golden color.
• Fresh parsley: Finely chopped and stirred into the crumble at the last second, it adds a fresh herbal note that balances the richness.

Instructions

Roast the celeriac until golden:

Preheat your oven to 200°C and spread the diced celeriac on a baking sheet with a drizzle of olive oil. Roast for 25–30 minutes, stirring halfway through, until the edges turn golden and caramelized—this is where the real flavor develops, so don't skip it or rush it.

Build the soup base:

While the celeriac roasts, heat olive oil in your pot and sauté the diced onion and minced garlic over medium heat for 3–4 minutes until they're soft and fragrant. You'll know it's ready when the kitchen smells sweet and inviting.

Combine and simmer:

Add your roasted celeriac and diced potato to the pot, pour in the vegetable broth, and bring everything to a gentle boil. Then reduce the heat and let it simmer quietly for 15–20 minutes until the vegetables are so tender they practically fall apart at the touch of a spoon.

Toast the hazelnut crumble:

While the soup simmers, roughly chop your hazelnuts and toast them in a small skillet with butter over medium heat for 2–3 minutes—listen for when they stop sizzling and smell deeply toasty. Stir in the fresh parsley and a pinch of salt, then set aside to cool slightly.

Blend until silky smooth:

Once the vegetables are completely tender, use an immersion blender to puree the soup directly in the pot, moving it through the liquid until it's completely smooth and velvety. If you prefer, you can carefully transfer it to a stand blender in batches, which some people find gives an even silkier result.

Season and finish:

Stir in your cream (if using), the nutmeg, salt, and pepper, and taste as you go. Reheat gently if the soup has cooled during blending, but don't let it boil once the cream is added.

Serve with celebration:

Ladle the soup into warm bowls and sprinkle the hazelnut crumble generously over the top—the contrast of silky soup and crunchy topping is the whole point. Serve immediately while the crumble is still crispy.

Save

My mother tasted this soup once and said it reminded her of restaurants she loved in Brussels, which was funny because I'd never told her where the celeriac came from. There's something about roasted celeriac that feels both grounded and refined, humble and special all at once.

The Magic of Roasting Root Vegetables

Roasting transforms ordinary roots into something tender and caramelized—the dry heat of the oven draws out natural sugars and deepens flavors in ways boiling simply can't match. I learned this years ago when I made celeriac soup the quick way, throwing raw diced pieces straight into broth, and the result felt thin and one-dimensional by comparison. Now I roast almost every root vegetable soup I make, even when it adds thirty minutes to the process, because that time in the oven is when the real alchemy happens.

Texture Contrast as a Cooking Principle

Smooth soups can feel monotonous if served alone, which is why that crunchy hazelnut topping isn't just decoration—it's essential architecture. The toasted nuts and parsley give your mouth something to do, something to anticipate, making every spoonful feel intentional rather than passive. This is a lesson that applies far beyond this single recipe: think about building textural interest whenever you plate something, whether it's adding croutons to smooth bisques, toasted seeds to creamy dips, or crispy fried onions to silky hummus.

Adapting This Soup for Different Tables

The beauty of a vegetable soup base is its flexibility—I've made this exact recipe vegan by swapping the cream for oat milk and the butter for olive oil, and it lost nothing in translation. One autumn, I added a handful of fresh sage leaves to the sauté, another time I stirred in a touch of white miso at the end for umami depth, and once I finished it with truffle oil because I was feeling decadent. The foundation is strong enough to support experimentation without losing its essential character.

• For a lighter version, skip the cream entirely or use just a splash of plant-based milk for silkiness.
• Pair it with sturdy bread like sourdough or rye, which stands up beautifully to the soup's creamy texture.
• Make this soup ahead and refrigerate for up to four days—reheat gently, and top with fresh hazelnut crumble when serving rather than making it ahead.

Save

This soup has become my quiet anchor when the season shifts and everything feels a bit uncertain. There's something grounding about standing at the stove stirring a pot that will soon nourish the people around your table.

Recipe FAQs

→ Can I make this soup without roasting the celeriac?

Yes, you can skip roasting and add raw diced celeriac directly to the pot with the potato. However, roasting caramelizes the celeriac and develops deeper, sweeter flavors that make this soup exceptional.

→ What can I substitute for hazelnuts in the crumble?

Almonds, walnuts, or pecans work beautifully as alternatives. Toast them the same way until golden and fragrant. Each nut will bring its own unique flavor profile to the dish.

→ How do I make this soup vegan?

Replace the heavy cream with coconut cream, cashew cream, or oat cream, and use olive oil instead of butter for the hazelnut crumble. The soup will remain creamy and delicious.

→ Can I prepare this soup in advance?

Absolutely. The soup keeps well in the refrigerator for up to 4 days. Store the hazelnut crumble separately in an airtight container to maintain its crunch, and add it just before serving.

→ Why add potato to celeriac soup?

Potato adds body and creaminess to the soup, helping achieve that silky smooth texture when blended. It also mellows the earthy flavor of celeriac while providing natural thickness without excess cream.

→ What does celeriac taste like?

Celeriac has a mild, earthy flavor with subtle celery notes and a slightly nutty undertone. When roasted, it becomes sweeter and more complex, making it perfect for creamy soups.